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In vitro fertilization
In Vitro Fertilization (IVF) is a technique whereby egg cells are
fertilized outside the mother's body due to conception being
impossible by normal intercourse. "In vitro" is Latin for "in glass",
referring to the test tubes.
The technique was developed in the United Kingdom by Doctors Patrick
Steptoe and Robert Edwards. The first so-called "test-tube baby",
Louise Brown, was born as a result on July 25, 1978 amid intense
controversy over the safety and morality of the procedure. The first
successful IVF treatment in the US took place in 1981, and there have
been 45,000 babies born with the aid of IVF treatment since then. In
brief, the process involves removing ova (eggs) from the woman's body
and letting sperm fertilize them in a fluid medium. The fertilized
eggs are then transferred to the mother's uterus where normal
development occurs. IVF is used commonly when the father's sperm count
is low or the woman's fallopian tubes are blocked.
Technique
Ovulation induction agents, such as Pergonal are usually given to the
mother 8-10 days before treatment, as they allow larger numbers of
eggs to be recovered, improving the chances of a successful
fertilization. Before the development of such drugs few eggs would be
retrieved because it required careful monitoring of the mother's 'LH
surge' in order to recover eggs at the right time. This also often
resulted in the performing of egg retrievals in the early morning or
night time because of the unpredictability of such an occurrence. As
well as 'superovulation' inducing drugs, gonadotropin releasing
hormone agonosts carefully control the timing of retrieval by
preventing any unexpected LH surges.
The eggs can be retrieved from the mother using the more common
sonographic technique involving an ultra-sound guided needle piercing
the vagina. The follicles of the woman are punctured and the woman's
follicular fluid is removed and placed in an incubator. Laparocopic
egg recovery involves retrieval through an incision in the abdomen.
This is used in women who also require a simultaneous assessment of
their pelvic anatomy through a diagnostic laparoscopy.
Semen is also taken from the husband. It can be analysed using 'sperm
penetration assays', where some sperm is checked to see whether it can
puncture a zone-stripped hamster egg. The sperm can also be cultured
to detect bacteria which can reduce the chances of pregnancy.
The sperm and the egg are incubated together (at a ratio of about
75,000:1) in the culture media for about 18 hours. The eggs and sperm
should fertilize in the usual way in this media (see fertilization),
but if this is not possible, assisted fertilization techniques -- such
as injecting the sperm directly into the egg using intracytoplasmic
sperm injection (ICSI) techniques (see below) -- may be used. They are
then passed to a special growth medium and left for 40 hours until the
eggs have become pre-embryos.
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The fertilized eggs are transferred to the woman's uterus through a
thin, plastic catheter, which passes through her vagina and cervical
canal. Often, multiple embryos are passed in to the uterus to improve
chances of successful pregnancy. If this procedure is unsuccessful,
the mother has to be given one month for recovery before the IVF
egg-extraction procedure is repeated. This may be avoided by freezing
embryos in liquid nitrogen when they are fertilized, and transferring
them during the natural ovulation cycle again.
The mother has to wait two weeks before she returns to the clinic for
the pregnancy test. During this time she can boost the chances of
pregnancy by continuing to take progesterone - which keeps the uterus
lining thickened and suitable for implantation to occur. The chances
of a successful pregnancy is approximately 20 per cent for each IVF
cycle.
Developments
Intracytoplasmic sperm injection (ICSI) is a recent development
associated with IVF which allows the sperm to be directly injected in
to the egg. This is used for sperm which has problems penetrating the
egg and results in success rates equal to or higher than normal
fertilization.
Gamete Intra Fallopian Transfer (GIFT) is a similar procedure to IVF,
which place harvested eggs and sperm straight in to the fallopian
tubes where it is hoped they will fertilize naturally.
Ethics
Certain ethical problems have been raised primarily due to technology
being developed which has enabled the extracted embryos to be frozen.
This was widely publicised when a Californian couple died in a plane
crash without leaving instructions on what to do with the frozen
embryos they had left in an Australian clinic. This situation has been
largely solved by consent agreements given by couples before they
undergo the procedure.
The use of frozen embryos that are no longer needed by the mother for
research (for example stem cell research) is a hotly contested issue.
A lot of the problem for some people is due to the embryos being
destroyed during the course of research. Some groups protest that
these embryos have the right to life, whereas other scientists reply
that they would have been destroyed anyway.
Another problem brought up by the use of IVF is the unconcentional
possibilities regarding who uses the technique. In 2001, a French
woman received worldwide publicity when she posed as the wife of her
brother in order to give birth to a donor egg fertilized by his sperm.
Some saw this as a form of incest; others thought it prove
psychologically unhealthy for the child when he learned how he was
delivered; whereas other people simply couldn't see anything wrong
with the situation.
The use of IVF provides a greater range of options for single people
and same-sex couples wishing to have children. Although both groups
already raise children, IVF makes the option much simpler and could
make the option widespread. Some people object that this could give
psychological problems to the child if they grow up without a
mother/father role-model.
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